1. Field of the Invention
The present invention relates to a magnetic tape cartridge and, more particularly, to a magnetic tape cartridge in which a single reel wound with a magnetic tape is rotatably housed or accommodated within a generally rectangular cartridge case.
2. Description of the Related Art
Conventionally, there is known a magnetic tape cartridge of a type in which a single reel wound with a magnetic tape is rotatably housed in a cartridge case (hereinafter referred to as a one-reel type) as one used as a storage medium employed for an external storage apparatus such as a computer.
Functions of the above-mentioned magnetic tape cartridge of the one-reel type will be described referring to a representative example of its configuration. FIG. 7 is a perspective view showing an external appearance of a conventional general magnetic tape cartridge of the one-reel type. FIG. 8 is an exploded perspective view showing a schematic configuration of the conventional magnetic tape cartridge shown in FIG. 7.
In the magnetic tape cartridge 60 shown in FIGS. 7 and 8, a magnetic tape 30 is wound around a single reel 56, which is composed of a lower flange 24 and an upper flange 54 being bonded by ultrasonic welding or the like, and the reel 56 rotatably housed in a cartridge case 52 that is composed of an upper case 52a and a lower case 12b being fastened to each other by machine screws (not shown) or the like.
Here, the above-described lower flange 24 is composed of a cylindrical reel hub 24a around the circumference of which the magnetic tape 30 is wound and a flange portion 24b projecting from the lower end circumference of this reel hub 24a in the radial direction, which are integrally molded with synthetic resin. A reel plate (not shown) or the like for magnetically joining a rotary driving unit for rotationally driving the reel 56, which is provided in a drive mechanism (hereinafter referred to as a drive) of a recording/reproducing apparatus such as an external storage apparatus, is attached on the lower surface of the lower flange 24, that is, on the bottom external surface of the reel hub 24a. 
The above-mentioned magnetic rotary driving unit engages with a driving gear formed around the lower surface of the reel plate to thereby rotate the reel 56. Simultaneously with this, a leader block 32 or the like to be described later is drawn out to a predetermined position in a tape travelling path of the drive, whereby data can be read from and written in the magnetic tape 30.
When the magnetic tape cartridge 60 is not used, the leader block 32 (a unit with which the drive having loaded the magnetic tape cartridge 60 introduces the magnetic tape 30 into the tape travelling path within the apparatus) is held at an opening 44 for drawing out the magnetic tape 30, which is formed on one side wall surface of the cartridge case (hereinafter also referred to simply as a case) 52, with the magnetic tape 30 being completely wound around the reel 56.
That is, when the magnetic tape cartridge 60 of such a one-reel type is set in the drive of the external storage apparatus, the magnetic tape 30 wound around the reel 56 is drawn out from the case 52 by the tape driving mechanism on the drive side and thus information is recorded in a magnetic recording unit of the external storage apparatus (or information already recorded is read out in a reproducing unit). Then, after such objective processing is finished, the magnetic tape 30 is rewound around the reel 56 in the magnetic tape cartridge 60 to be housed in the case 52 again.
Incidentally, a magnetic tape cartridge of such a one-reel type has a disadvantage in that its thickness (i.e., its height in the reel axial direction) is large. In addition, since the magnetic tape cartridge requires many components, it is not easy to reduce its manufacturing cost.
The former disadvantage of large thickness poses a significant problem not only for the magnetic tape cartridge but also for the entire system in that it is inevitable to enlarge the driving mechanism on an external storage apparatus side as well, in which the magnetic tape cartridge is loaded to be used. In addition, the latter disadvantage of the large number of components contributes to the difficulty in decreasing the costs of components and the costs for assembling the magnetic tape cartridge 60.
These disadvantages are ultimately attributable to the fact that the conventional magnetic tape cartridge is configured to house a reel wound with a magnetic tape in a cartridge case or a cassette case (hereinafter referred to simply as a cartridge case) and to rotate the reel within the cartridge case, as in the cases of other well-known magnetic tape cartridges or magnetic tape cassettes and the like.
That is, from a conventional and ordinary point of view, a reel wound with a magnetic tape and a cartridge case that is a protecting unit and houses the reel exist for entirely different reasons (purposes) and are independent components, and these components are combined to construct a magnetic tape cartridge and a magnetic tape cassette.
Therefore, although these components are provided with parts that overlap with each other, such parts are left as they are. Moreover, conventionally, there have been made no discussions as to how the overall construction should be designed by fundamentally reviewing functions of these components.
In addition, in the magnetic tape cartridge 60 of the one-reel type having the above-mentioned construction as illustrated, the above-mentioned opening 44, which becomes a passage for drawing out and rewinding the magnetic tape 30, is provided relatively close to the corner of the cartridge case 56. Thus, if the magnetic tape cartridge 60 is accidentally subjected to careless handling such as rough handling or dropping thereof, the opening 44 is likely to be damaged.
That is, in the conventional magnetic tape cartridge 60, since the above-mentioned opening 44 is provided relatively close to the corner of the cartridge case 56 due in part to the configuration of the drive side, the magnetic tape cartridge 60 is inevitably low in mechanical strength and rigidity due to its structure and is likely to be damaged when it is subjected to careless handling.
The present invention has been devised in view of the above and other drawbacks, and it is a first object of the present invention to provide a magnetic tape cartridge that can eliminate the above-mentioned disadvantages in the prior art and reduce the number of components and costs as well as its overall thickness while maintaining respective functions of a reel and a cartridge case when constructing the magnetic tape cartridge by combining the reel and the cartridge.
In addition, it is a second object of the present invention to provide a magnetic tape cartridge that is made unlikely to be damaged even if it is subjected to careless handling such as rough handling or dropping thereof.
In order to attain the first object described above, the first aspect of the present invention provides a magnetic tape cartridge comprising: a single reel including a circular lower flange in which an engaging portion for engaging a rotary shaft of a recording/reproducing apparatus is centered, and a circular upper flange which is arranged so as to be opposed to the lower flange and has an outer diameter larger than the outer diameter of the lower flange; a magnetic tape which is wound between the upper flange and the lower flange; and a cartridge case within which the single reel is rotatably accommodated and which includes a lower case into which the rotation shaft is inserted and which has a first opening at a position corresponding to the engaging portion of the lower flange, and an upper case which has a circular second opening having an inner diameter larger than the outer diameter of the lower flange but smaller than the outer diameter of the upper flange; wherein the upper flange closes the circular second opening of the upper case to form a central portion on an upper side of the cartridge case.
That is to say, the magnetic tape cartridge of the first aspect of the present invention comprises a generally rectangular cartridge case in which a single reel wound with a magnetic tape is rotatably housed, wherein one of two flanges composing the reel constitutes a central main portion of one side (an upper side) of the cartridge case. It is preferable that the central main portion of a side, which becomes an upper side when the magnetic tape cartridge is loaded into a recording/reproducing apparatus, is constituted by the upper flange that is one of the two flanges composing the reel.
Preferably, the upper case comprises a circular cutout portion which is provided on an upper side of the upper case along the circular second opening and has an inner diameter larger than the outer diameter of the upper flange, and the upper flange comprises an annular stepped portion which is provided circumferentially on a lower side of the upper flange and fits in the circular cutout portion of the upper case from an upper side.
That is to say, it is preferable that a circular cutout portion larger in size than the upper flange is formed on the upper surface of the cartridge case, and a stepped portion of the upper flange formed to have a step fits in the cutout portion.
Preferably, a movement preventing unit for preventing relative movement (pivot or rotational movement, rotation) of the upper case of the cartridge case and the upper flange is formed on an upper side of the circular cutout portion of the upper case and a lower side of the stepped portion of the upper flange abutting the upper side of the circular cutout portion.
Preferably, the single reel is mounted in the cartridge case by means of its dead weight and the movement preventing unit functions also by means of the dead weight of the reel and a weight of the magnetic tape wound around the reel.
Preferably, at least two reel engaging units are provided on an upper side of the upper case to engage the upper flange and prevent the single reel from being unwantedly disengaged from the cartridge case.
Preferably, the reel engaging unit includes an urging unit for urging the upper flange toward the upper case.
Preferably, engagement of the upper flange of the single reel by the reel engaging unit is released when the magnetic tape cartridge is loaded into the recording/reproducing apparatus. The reel engaging unit may be movable within an identical plane such that the engagement of the reel is released in case of loading the magnetic tape cartridge into the recording/reproducing apparatus such as an external storage apparatus.
Preferably, a magnetic tape drawing-out port, which becomes a passage for drawing out the magnetic tape from the cartridge case and rewinding the magnetic tape into the cartridge case, is provided on a side surface of the cartridge case at a position apart from a corner of the cartridge case.
In order to attain the second object described above, the second aspect of the present invention provides a magnetic tape cartridge comprising a generally rectangular cartridge case in which a single reel wound with a magnetic tape is rotatably housed, wherein a magnetic tape drawing-out port, which becomes a passage for drawing out the magnetic tape from the cartridge case and rewinding the magnetic tape into the cartridge case, is provided on a side surface of the cartridge case at a position apart from a corner of the cartridge case.
In each aspect of the present invention, it is preferable that the magnetic tape drawing-out port is provided between a position corresponding to a screw hole used for assembling upper and lower cases and provided in the corner of the cartridge case, and a position corresponding to a reference hole provided in the vicinity of a central portion of the cartridge case.
Preferably, a central position of the magnetic tape drawing-out port is located at a position apart from the corner of the cartridge case by a distance equivalent to approximately one quarter of an edge length of the side surface of the cartridge case.
It should be noted that the first and second aspects of the present invention described above can obtain the corresponding effects to the combination of the above first and second aspects by applying the combination.